


Grounded

by Luki



Series: Dr. Stone Week: Luki Edition [6]
Category: Dr. STONE (Anime), Dr. STONE (Manga)
Genre: Alternate Universe - Urban Fantasy, Angst, Dr. STONE Week, Father-Son Relationship, Gen, Selkies, day 7 - Foundation
Language: English
Status: Completed
Published: 2020-07-04
Updated: 2020-07-04
Packaged: 2021-03-04 20:33:41
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 7,157
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25072417
Author URL: https://archiveofourown.org/users/Luki/pseuds/Luki
Summary: Selkies are rare in Japan. While waterborne make up 40% of the population in Japan – nearly 10% higher than the global average - most of the waterborne are merfolk, traditionally saltwater or tropical breeds.  Being of the seal line suggests foreign blood – even if the very nature of the selkie means it can show up quite randomly. Just walking down the street with his pelt wrapped around his waist gets him a ridiculous number of double takes...---AKA, a Selkie!Senku AU
Relationships: Ishigami Byakuya & Ishigami Senkuu
Series: Dr. Stone Week: Luki Edition [6]
Series URL: https://archiveofourown.org/series/1811146
Comments: 12
Kudos: 217
Collections: Dr. Stone Week 2020, The Great Reads





	Grounded

**Author's Note:**

> Last entry for the Dr. Stone Week (Day 7: Foundation - Fantasy vs. Science)
> 
> WHAT THE HELL POSSESSED ME TO WRITE SO MANY DAMN AU'S! Gonna be quite grateful to go back to my Villainness and KHR fics after this monster week. Hope you enjoy!

Selkies are rare in Japan. While waterborne make up 40% of the population in Japan – nearly 10% higher than the global average - most of the waterborne are merfolk, traditionally saltwater or tropical breeds. Being of the seal line suggests foreign blood – even if the very nature of the selkie means it can show up quite randomly. Just walking down the street with his pelt wrapped around his waist gets him a ridiculous number of double takes.

Senku doesn’t really mind though. The fact that his pelt is detachable means he’s not anywhere near as dependent on water as most. His friend Taiju is a freshwater mer, and regularly finds himself wading in the nearby river to get rid of the edge at least once a month, while Senku could theoretically go a lifetime with only mild discomfort. Also, he’s not alone – Byakuya is a selkie too. Sometimes, he wonders if that’s why the man took him in, but it’s not something he let’s himself worry about.

Growing up, Byakuya did everything he could to encourage Senku’s scientific passions, but also wouldn’t let him neglect the more fantastical part of himself. Every month or so, the two of them would hire a car, head to the ocean, and just spend the weekend exploring the coast. The two of them would swim as far into the ocean as they dared, and spend the nights staring up at the sky, free from the lights of the modern world. Then they’d swim back, and Senku would catalogue the reefs and fish, and then the cliffs and fauna of the route, mentally collecting a map so that next time, they can go even further. He’ll never voice it to the old man, but he counts the seconds till each trip, the highlight of his month.

But one trip, as they’re driving out, Byakuya tells him the news. JAXA has started looking for astronaut candidates. If he succeeds, Byakuya’s going to be spending more time in America, and these swims are going to become a lot rarer.

“ If I make it, you’ll have to handle more of your swims solo,” Byakuya tells him, looking a little nervous. “Can you do that? I don’t want to come home and find you haven’t gone swimming in anything bigger than the bathtub.”

“ Of course I can,” Senku replies, rolling his eyes to hide the sinking feeling in his stomach.

“ Maybe you can take someone with you?” Byakuya says. “Could Taiju...no, he’s freshwater, so that’s no good.”

“ I’ll be fine,” Senku insists. “And besides, isn’t it  _ if _ you pass?’ Pretty arrogant to make plans when you haven’t even got the job yet.”

He grins when Byakuya starts pouting and complaining to the air about ungrateful geniuses. The swimming portion of the test is always a natural disadvantage for non-merfolk, because their natural genetics give them an edge that other shape shifting breeds don’t. Granted, mer's can’t shift their legs into tails for the exam, but the upper part of their body doesn’t change too much in either form – their torso upwards is designed to fly through water. Senku has seen Byakuya loop and spin and shoot through water at 50 miles an hour...but only once he’s pulled on his pelt and gone from an easygoing, middle aged teacher to a heavy, streamlined, aquatic predator. Swimming fully clothed is literally what Selkies have evolved  _ not _ to do.

...Huh, that could be an interesting experiment. And honestly, he doesn’t want to deal with Byakuya moping over failing again.

But for now, he shakes the thoughts out of his head, and focuses on the road ahead. If this is the last trip they’ll have for some time, he doesn’t want to miss a second of it.

* * *

Byakuya, by some insane miracle, does in fact pass the entrance interview, and Senku finds himself living the latchkey life. Not that Byakuya lets him go very long without a phone call, but even he’s always known Senku was a naturally self sufficient brat.

He also keeps to his promise to go out swimming, though he generally stays closer to home and only for an afternoon. As much as he loves the feeling of being wrapped in his pelt and swimming through the ocean, seals have always been social creatures. Selkies are no different, and even with his anti-social tendencies, Senku is happiest when with his pod. The ones he trusts more than anything – Taiju and Byakuya. Swimming solo just isn’t the same.

He mentions it to Taiju once, when the two of them are putting together a prototype rocket – and the mer takes it upon himself to drag Senku out to the artificial lake every two weeks to swim with him. While he complains and rants about all the lost experiment time at every opportunity, he can’t deny he’s grateful.

* * *

In middle school, Taiju introduces Senku to another waterborne – a beautiful naiade called Yuzuriha. She brings with her tiny dolls for the rocket Senku is putting together, and her eyes light up when she spots Senku’s pelt, poking out from his bag.

“ Is it yours?” she asks. “I’ve never seen one before. They say a selkies pelt is softer than any other fur.”

“ That’s a myth,” Senku says. “It’s no finer than a normal seal. I’ve tested it.”

Yuzuriha immediately blushes, and after glancing over at Taiju, asks - “can I touch it?”

Senku raises an eyebrow, and the girl immediately drops her head.

“ Sorry, that was too forward of me,” she says.

“ It’s not that,” Senku says. “You’re just the first person to ask first.”

There’s a reason he keeps it hidden in a bag, and it’s not just because he doesn’t want it getting damaged in the lab. Normal humans, sometimes referred to by waterborne as ‘grounded’ are definitely worse for it, but mers are close behind. The second anyone sees it draped around his waist or his shoulders, they take it as an open invitation to touch. As if it’s nothing more than a fancy scarf or shirt. Like he can’t feel every single finger that brushes along the fur – he has enough trouble when his pencil case dislodges and knocks against it in the bag.

The girl however, looks shocked.

“ Really?” she says. “But...it’s part of you. You can’t just touch someone without their permission.”

Senku grins, and looks over at Taiju, who's wearing the most puppy dog expression he’s ever seen the guy wear. His ears are even starting to spike, revealing blue and purple scales.

Taiju might be a dumb oaf, but he’s picked a winner this time.

“ You can touch just above the flipper,” he offers, walking past and grabbing the bag, shifting the pelt out to reveal the specified area. “Go ahead.”

Yuzuriha’s face lit up, and gingerly pressed one finger against the pelt.

“ Oh...it really is soft,” she gaps. “Like velvet.”

She brushes it downwards, and Senku smiles as he feels the touch ripple down his arm. Yuzuriha must notice something, because her hand instantly jerks away.

“ You can feel that?” she asks, and Senku nods.

“ Yup. No matter how far away a selkies pelt may be, it’s still part of us,” he says. “I’ll feel every touch. It’s one of the reasons why we don't like people touching them.”

Yuzuriha blushes bright red, and starts apologising furiously. Senku just laughs and waves her embarrassment off.

“ Hey, I gave you permission, don’t worry about it,” he says, and picks up one of the dolls. “Now, how do you feel about rockets?”

* * *

They’re wandering down a hill they’d been scouting for the rocket launch, when they’d somehow got onto the topic of the history of waterborne. Senku isn’t entirely sure how – he’d been going over calculations in his head, and when returned to reality, Yuzuriha was finishing off a story regarding merfolk and their contribution to the pirate era.

“ Speaking of,” Yuzuriha had started, once she realised Senku was finally listening in. “How much truth is there to the selkie myth? I remember there was a huge push in the 60’s regarding rights, but it wasn’t big in Japan.”

Senku smirks. “Yeah, that tale ten billion percent got mistranslated at some point, but it took forever for people to admit it.”

“ So if you steal a selkies pelt, they don’t have to stay with you?” Yuzuriha presses. Taiju just laughs.

“ No way,” he says. “Senku’s let me carry his pelt a bunch of times, and he can always wander off.”

Yuzuriha glances between the two of them, and Senku shrugs.

“ The story is that a fisherman spots a seal shedding their skin and becoming a beautiful woman. He’s so enamoured, he grabs her pelt and runs away. The woman chases him, asking for it back, but he refuses, and later marries her. They have a bunch of kids, and one of them tells her about the pelt in the attic. Once she knows where it is, she grabs it, and returns to the sea, never to be seen again. At least, that’s the story most people know.”

Yuzuriha nods. “There were debates on whether or not a selkie could be enslaved if you took their pelt. And if you could ever be in an equal relationship.”

She frowns. “There were rumours in school that it’s why you weren’t interested in anyone. I’m guessing that’s not the case?”

Senku and Taiju both burst into laughter.

“ Nope. Ten billion nope,” Taiju says.

“ I’m not interested in a relationship because they’re utterly pointless,” Senku tells her, then stops and looks up at the sky. Soon the stars will be out.

“ A selkie’s pelt is literally part of them. To take one without permission is the same as assaulting a person, but to be handed it willingly is a sign of trust. It’s supposed to be a great honour, to be trusted with someone’s pelt.”

“ Then, the woman in the story?”

“ If the fisherman really stole the pelt, the selkie or her family would have killed him,” Senku explains. “He couldn’t make her stay, but he might have thought she was compelled to since she didn’t leave. But I find it hard to believe she’d stay long enough to have several kids before hunting down her pelt. I’d have torn the house apart looking for it. If it was hidden in the attic, she’d have found it before the first kid popped out. But the story persists that if you steal a selkies pelt, they become your slave.”

Even though it’s not true, the myth has even leaked into legislation. The penalty for stealing a pelt, or causing damage to one, is considered high larceny and grievous bodily harm. But that’s also made them highly attractive to the right markets – and the dangerous allure means people desperately want to touch on a regular basis. Senku always makes a point to hide his under a jumper or coat whenever possible.

“ Selkies have their own version of the story,” he offers, when he realises Yuzuriha has been rather quiet. “In our version, the fisherman talks to the selkie, and they fall in love. On their wedding day, the selkie gifted him her pelt, the greatest gift she could offer him. She trusted that he would always give it back, because he would trust that she would always return. The one time he refused, would be the one time she didn’t.”

Yuzuriha’s starts to smile. “That’s lovely. I like that version a lot more.”

Senku grins.

“ In reality, giving pelts as romantic gifts usually ends badly,” he warns her. “These days it’s more common to offer them to family members, or to friends-”

He half heartedly shoves Taiju’s shoulder as they reach the street. “-On a short term basis.”

“ Love ya too, Senku,” Taiju cheers.

* * *

It’s almost strange how quickly the days pass after that. Rockets are launched, exams are taken, and they leave middle school for high school and its new experiences. Senku waltzes into the science club and essentially takes it over in a matter of hours – without even trying, he’d like to add. Taiju goes from just admiring Yuzuriha to full on swooning, barely able to keep human form whenever she’s in the vicinity and dragging Senku out to the nearby lake to calm down nearly every other week, and Yuzuriha folds into their duo as if she’d always been there – barely batting an eye at Senku’s science explanations or Taiju’s expressive personality, and joining them at the lake more often than not.

Byakuya changes too, as his launch date grows closer and closer, his calls become more frequent, and a week before he has to fly out to the launch site, he comes home to see Senku – driving them out to the other side of Japan and swimming as far as they can, till there’s no sign of human civilisation, not even a plastic bottle.

The two of them glide through the currents, the larger Byakuya playfully nudging the more streamlined Senku along, as he tries to nip the elder for his antics. They find a shoal of fish, and move in perfect harmony, hunting the weak points and swimming home with full bellies. When they crawl back onto the beach and shed their skins, they stare up at the sky with smiles, and Senku silently thinks that if time stopped right now, he’d probably be okay with that.

They drive home in silence, but the night before he flies out, Byakuya cooks dinner, and at the end of the evening, hands Senku his pelt.

“ Take care of it for me, will you?” he asks, face sad. “I know it’s sappy, but I’d feel better if I knew I wasn’t leaving you completely alone.”

Senku holds it delicately, making sure not to touch it more than he has to, since Byakuya always jokes that he’s ticklish. In fact, Byakuya’s shoulders are already twitching, and Senku carefully puts the pelt down on the table.

His reaction clearly isn’t what Byakuya was wanting, because his face falls.

“ Hey, come on Senku, I know you’re not the most emotional guy, but-”

He trails off when Senku merely kneels down, and lifts up a box he’d been hiding under the table himself. Byakuya’s face is a picture when he lifts the lid and finds Senku’s pelt inside.

“ Sure, so long as you take care of mine,” Senku promises – and then immediately braces for Byakuya’s flying lunge and hug.

“ SENKU!”

“ Ack! Come on old man! I still need my spine!”

* * *

A selkie and their pelt have a connection that science is still fervently studying. Senku supports the hypothesis that it’s similar to a phantom limb – only that the limb is still in existence.

Every night since Byakuya left, the old man makes a point to take out Senku’s pelt and place a handprint on his back, making sure Senku knows he’s thinking of him. It’s utterly unnecessary and ridiculous and ten billion percent Byakuya, and Senku is going to rib him mercilessly when he gets back. But it’s also pretty useful. After every handprint, he takes Byakuya’s pelt, and starts tracing on his fin.

‘ _ Old man, write down any differences in feeling that you get,’ _ he writes. ‘ _ what time are you feeling this? What time is it there? Is there any time delay with distance?’ _

He’s sure Byakuya’s probably laughing and scratching his arm furiously, but Byakuya knew what he was getting into when he left his pelt here.

A few hours after the news sites report the successful launch, he hides the shudder when he feels something brush against his back, but rolls his eyes when he realises the feeling is drawing out a smiley face – followed by a few words.

‘ _ HI. I AM LILLIAN. UR DAD SAYS HI!’ _

Senku silently laughs to himself. Byakuya is such a sap – but at least it’s giving him some good data.

Hopefully his old man will be smart enough to hold back on introducing his fellow astronauts until school is let out. For now, he’s got to focus on his experiments. The petrified swallows need his complete attention.

* * *

His first thought when Senku breaks out of the stone, once he’s established the time that’s passed, is ‘ _ where is Byakuya’s pelt?’ _

He’d been carrying it on him ever since Byakuya left, in a bag, carefully wrapped so he couldn’t damage it or distract Byakuya at the wrong time. The bag will have long since rotted away, but what about the pelt? Was it petrified? It’s next to impossible to destroy a pelt – at least, not while the owner is alive.

He needs to find it – but right now, it’s ridiculously low on his list of necessities. Once he has fire, shelter, food, weapons...and help, then he can look…

* * *

He can’t find it.

Even with Taiju finally breaking free of the stone and giving Senku the desperately needed manpower, he can’t locate Byakuya’s pelt. He knows he’s looking for a rock, rather than fur, because he’s managed to find a statue with a stone pelt around her waist, but no matter where he looks or has Taiju digs, it’s nowhere to be found.

But he does find rocks. Small, shattered, eroded rocks, where he hypothesised the pelt would likely have ended up. When he finds the strength to try the nitric acid, the rock turns to fur.

It’s agonising – while he knows Byakuya had next to zero percent chance of surviving the petrification (if everyone on the space station was petrified, it’s likely crashed out of orbit and burned to ash when it entered the atmosphere, and if they weren’t, they were trapped in space with no ground support. If they’d made it down in one piece...well, it’s been 3700 years), he was supposed to be taking care of it.

...And, on a more darker note, this was the only pelt he had. His is god-only-knows-where and almost impossible to locate. It might even have been destroyed. Sure, pelts are notoriously hardy, but he’s also pretty sure nobody’s ever tried burning one in a crashing space station before – and if it was petrified, it could have been shattered.

Selkies are unique among the waterborne because you don’t always have to be born one. Pelts are not normally transferable, but there’s always been a strong familial trait to them. If there’s a close enough bond, another selkie or even another human (provided there’s at least  _ some _ waterborne blood in them) can inherit it once the owner passes. It’s sometimes how selkies pop up in relatively human family lines. Senku and Byakuya might not share blood, but the bond was there – he could ten billion percent have worn Byakuya’s had the man passed on. If he couldn’t wear it, he would know the old man still out there.

Without it? Not only can he know if he will ever see his father again, but he’ll never be a selkie again. An intrinsic part of him, gone forever.

He’s grounded.

* * *

He manages to keep Taiju from realising the truth until they revive Tsukasa, a man so unbearably human it’s almost painful to watch.   


Not that he’s a bad guy, that’s not the issue. But waterborne will always have a connection to the water that the grounded can never fully understand. When he watches Taiju shift and jump into the ocean for the first time, he sees Senku standing on the shore, letting the water pool up to his mid calf, and quickly makes the connection.

“ You’re not going to join him?” he asks in his soft voice. “I don’t mind waiting here.”

Senku shakes his head. “That’s not really an option for me.”

Swimming without a pelt has never been Senku’s forte, and there’s a noticeable rip in the water – Taiju will practically have to carry him around, and he’s not going to ruin his friends' fun.

“ You can’t swim?” Tsukasa says, managing to get the right conclusion but the wrong explanation. “I can teach you-”

“ It’s not that,” Senku interrupts, crossing his arms. “I’m a selkie.”

He can practically feel Tsukasa’s eyes boring into his back at that revelation.

“ ...Did someone take your pelt?” is his next question, with a low baritone that suggests ill will to some fantasy villain in his head. Senku laughs despite himself.

“ Not exactly, and even if they had, I’d have yanked it back the second they tried,” he answers. “Lot of those myths are bunk.”

Tsukasa is still staring, and Senku starts looking up at the sky.

“ My old man, he had my pelt,” he explains. “He wasn’t in Japan when this happened.”

There. No need to go into the details. Tsukasa will realise what Taiju hasn’t, and he’s desperate to avoid that tragic revelation as soon as possible.

“ I’m sorry,” Tsukasa says, though Senku suspects he only says it to be polite. “Does it hurt, not having it?”

Senku shrugs. “Not physically. But yeah, it kind of sucks.”

He then turns out to the ocean, where Taiju is waving from the deep water.

“ Don’t tell the oaf,” he orders. “He’ll just cry about it, and there’s nothing he can do to fix it. We have enough issues without piling that on him.”

* * *

When he arrives at Ishigami Village one faked death later, he’s genuinely surprised at the number of selkie pelts wrapped around villager waists – even both guards at the bridge are sporting one. The population is about 50 people in total, but there’s 7 pelts that he can count. That’s an impressive number for such a small group, and he suspects a few inherited them. The rest of the waterborne are mostly freshwater, but every now and then, he hears a tune coming from the islands, suggesting one or two are also sirens.

His escort Kohaku, is human, though unlike Tsukasa, there’s definitely waterborne very recently in her family tree. He’s proven right when he learns her sister is the Village Priestess, and one of the sirens Senku can hear – though her sickness means her voice isn’t particularly strong. On the other side, the sorcerer she’d wanted him to meet, Chrome, is a freshwater, and irritated at another ‘sorcerer’ coming onto his turf – at least until Senku wins his collection out from under him.

He manages to keep his own lineage under wraps until they go hunting for iron sand – Chrome and Kohaku far more interested in a possible cure for Ruri, and making the natural assumption that he’s human. He tries to stick to the shore, while Chrome heads into the middle, scales on full display – but there really isn’t enough sand there, and Kohaku practically drags him in to help.

When he steps into the river, feeling the current running between his legs, they nearly buckle at the emotional hit his body has to handle. He ends up kneeling in the water, one hand clutching the magnet as he tries to get a handle on himself.

Dammit, with his pod, Taiju and Yuzuriha and Byakuya all gone, and no pelt, he hadn’t realised how much it was hurting.

“ Senku?” Kohaku asks, spotting his minor breakdown from where she’s collecting sand and walking over. “Are you okay.”

He sucks in a breath, and staggers to his feet. “Yeah, fine. That just hit me harder than I expected.”

She’s frowning, her head cocking slightly in confusion, and their conversation drags Chrome and the little siren they’d attracted over.

“ Are you waterborne?” she asks. “You’re acting like one of the mers when the winter season runs longer than usual and the ice doesn’t thaw.”

Senku grits his teeth. Dammit.

“ Wait, you’re not human?” Chrome asks. “But then, why not shift? Things would be a lot easier.”

Oh, if only. He chuckles, irritated that the sound is harsher than he’d like.

Senku sighs, but refuses to stop searching. “I’m a selkie, but when the petrification event happened, my old man and I had switched pelts. When I woke up, his pelt was gone, and I have no idea where mine ended up.”

The little siren, Suika, gasps in horror.

“ But then, if you don’t have your pelt, that means you can’t swim!”

Chrome and Kohaku look pretty horrified too.

“ Wait, can’t you use science to locate it?” Chrome asks. “Surely there’s got to be some way?”

“ Science can do a lot, but it can’t track down a piece of leather and fur,” Senku says. “Look, I've to come to terms with it. It’s not like I have time to go exploring the ocean anyway. I don’t need it the way you do, Chrome.”

“ But still...” Kohaku says, eyes very sympathetic for a human. “I know the hot spring water is one of the few things that still gives Ruri any joy. It broke her heart when she became too weak to go swimming in the lake any more.”

“ There are still ways I can go swimming,” Senku assures them. “It won’t be the same, but science can take humans places only waterborne can normally go. But for now, let’s focus on the iron.”

* * *

Asagiri Gen is a frustrating conundrum, who feels like he should be waterborne, but is also clearly human. No self-respecting mer would be walking on the ground barefoot if they didn’t have to, and he isn’t drawn to the water even when he’s worked to death.

Senku suspects he’s similar to most humans in the village – a human with a heavy waterborne background where the grounded genetics won out. Thankfully, he’s not nearly as malicious as he pretends to be, willing to help chase off Magma and convince the two brothers to work on the generator – curious enough to see if Senku will succeed despite the odds.

While Kinro and Ginro exhaust themselves running the generator, Gen chooses to match step with Senku, in a rare moment he is alone – all three members of the Kingdom of Science have a thing about leaving him by himself – to ask a question that’s clearly been on his mind.

“ How is it, being a selkie without a pelt?”

Senku smiles. “So, Tsukasa let it slip, huh? Or was it Taiju?”

“ Tsukasa,” Gen answers quickly. “He thought it would help me get inside your ead-hay.”

“ And did it?” Senku asks. Gen grins.

“ I found you, didn’t I?”

Senku rolls his eyes. “I’ll tell you what I keep telling everyone else. I’m fine.”

“I find that hard to believe,” Gen immediately quips. “Even if a selkie doesn’t need the water, you’ve lost something irreplaceable.”

“So will a lot of people,” Senku says. “I can live with this.”

He can live with it.

He  _ has _ to live with it.

* * *

Gen leaves, now a budding member of the Kingdom of Science, and the drug’s road map painstakingly gets filled in, especially when they recruit another selkie, the old craftsman Kaseki, until the only thing standing in their way is the tournament. While that doesn’t go  _ quite _ to plan – they finish the drug, Gen returns, Senku is declared Chief...and Senku learns for the first time, exactly where he’s been living for the last six months.

Ishigami Village.

Ishigami. The 100 th tale. A thousand questions suddenly given an answer.

Ruri tells him the story that has been passed down for generations. The story of a petrified world, of astronaut’s making a desperate attempt to make it to land, and of a man’s belief that his son would succeed where he failed.

When Ruri leads him to Byakuya’s grave and leaves him to mourn, Senku lets himself break down, and acknowledge what the story didn’t mention. The painful hidden message Byakuya hadn’t included. That Senku is the reason that the petrification lasted as long as it did.

_ Senku _ is the reason Byakuya never made it home.

Of the other five people aboard the space station, two were human, one was a siren, and the other two freshwater merfolk. None of them could have swam to Japan, or indeed anywhere else long distance. Not through ocean seawater. Only Lilian-the-siren and Byakuya-the-selkie could handle saltwater, and while the water might have been warm enough for a tropical species to handle, sirens cannot handle deep ocean. Selkies can, but Byakuya didn’t have his pelt – and while another waterborne, or even a baseline human, can sometimes inherit a pelt, it can’t happen while the current owner lives. Senku had held the one thing that could have got him to Japan’s shore at his side until the man’s death.

“ I’m sorry, old man,” he says to the awkwardly shaped rock, corroded over the years. “I’d say I wish things had gone differently, but I can’t think of a world where you wouldn’t have given me your pelt. You were sentimental that way. It’s why I knew I’d have to give you mine.”

He swallows the lump in his throat. “I know you couldn’t save my pelt, but thanks for the gifts. I’d have been completely screwed without them. So thanks, Dad.”

* * *

After the invasion, and Senku reveals his plan to create a cellphone, he doesn’t allow himself to wallow in the past. They don’t have the time – and with the frost setting in, the majority of merfolk can’t enter the water regardless.

Gen, to his surprise, settles into the village shockingly well. Kaseki in particular, seems to really taken a shine to him, which even  _ Gen _ seems to find rather surprising. Senku however, doesn’t – while Gen is very vocal about his often mentioned hatred for manual labour, he never shirks his duties, which definitely wins him some respect.

It’s probably how he’s able to convince everyone to put together the telescope. Granted, his silver tongue does most of the work, but it doesn’t hurt.

His confession regarding his feelings and respect for Senku are more of a surprise than the telescope, if he’s being honest. A welcome one – sometimes Senku looks back and wonders how the hell he manages to convince so many people to his side. He has never been a charismatic person, so how does he keep doing it?

* * *

One night, with the cell phone only a few days from completion, he’s up in the observatory with Gen, and the topic somehow rolls back to Senku’s missing pelt.

“ I won’t pretend to know what it’s like, to lose a part of yourself like that,” Gen says. “But I do know something about feeling like something’s missing. It’s not healthy to keep that pain locked away.”

“ I’m not locking it away,” Senku defends. “I’m processing it on my own terms. There’s not much else I can do.”

“ I don’t think you’re doing as well as you think you are,” Gen sing songs. “Do you know Kaseki is already preparing to leave his pelt to you?”

Senku stills. What?

“ Kinro also told his parents that if he should die before he marries, he wants it to go to the Chief’s ine-lay,” Gen continues. “Some of the other selkies have offered the same. All of them are angling to get you back in the water, whether you like it or not.”

“ That’s crazy,” Senku mutters, though there’s a bit of a smile on his face. “I didn’t even know that me being a selkie was common knowledge.”

“ Suika let it slip, I believe,” Gen admits. “And is it really so surprising? This village  _ adores _ you, and Kaseki has no family. Who else would he leave it to?”

Senku laughs. “Honestly, given how much of a soft spot he has for your whining ass, figured Kaseki would be leaving his pelt to  _ you _ . I’m ten billion percent certain there’s enough waterborne in you to make it work.”

He’s mostly just trying to change the subject – usually a futile effort when it comes to Gen when he’s motivated – and the mentalist chuckles.

“ Oh yes, me with a selkie pelt. Like my bloodline isn’t essy-may enough.”

And oh, Senku can’t let that one lie. It’s too good a lead into a question he’s always wanted to ask.

“ On that topic, I’ve got a question, Mentalist,” Senku says. “What exactly  _ are _ you?”

“ Hmm?”

Senku smirks at his confused look. “Don’t give me that. I know you too well by now. Sure, you’re human, but there’s something else in there, right?”

Gen blinks again, before letting the confusion leak away and laugh.

“ There’s no getting anything past you, is there dear Senku?” he says. “You’re not exactly wrong.”

He looks away, pretending to stare at the stars, before-

“ My father is a kelpie,” Gen tells him, and Senku raises his eyebrows. “While my mother was a ceasg.”

“ A kelpie and a ceasg?” Senku repeats with a disbelieving laugh. That’s one hell of a genetic pool – both are dying breeds and definitely found more in Europe than Asia.

Gen nods. “Oh yes. A lot of family on both sides were looking forward to bringing another of either into the world. As you can imagine, it was quite the disappointment when I ended up being uman-hay.”

“ They had to know the odds,” Senku replies. Quite a few of the ‘mer’ races don’t even specify any more, too much cross-breeding over generations. It’s why Selkies sometimes inherit pelts rather than bury them with the owner – the genes of most waterborne are recessive, and the population keeps dropping.

“ Of course they did. Didn’t stop them from having my darling little brother not ten months later,” Gen says, voice clipped. “Kelpie, by the way, and the darling of their eyes.”

Ten months. Ouch.

“ Don’t look so upset, it helped me out in the long run,” Gen says. “When you’re not wanted, you get very good at reading people to avoid trouble. Thankfully, my great aunt ripped them a new one, and did most of my raising – even bought me my first deck of cards. Between the three of them, my mentalist career was all but assured.”

That...probably explains more about Gen’s superficial personality traits than Senku needed to know. He never had a chance but to lean into the ego if he wanted to succeed.

He really had been lucky, when Byakuya had come to the orphanage for him. What would Senku have become, without the old man watching his back, making sacrifices so that Senku didn’t have to?

Did Byakuya die without ever knowing how grateful Senku had been, to have him as family?

* * *

With the creation of the cell phone, comes the revelation of story 14, and that has the village all stumbling into the graveyard, with Senku ripping up Byakuya’s gravestone.

“ There’s something inside here,” he tells them. “Kohaku, I need you to break it open, but do it delicately.”

The girl complies, going at it was fast, constant chips, until the surface shatters into a thousand pieces, revealing something tightly wrapped.

“ Huh, what is this?” Kohaku asks, pulling at the lump, and pulling at the thin protective layer – that Senku suspects might have been foil at one point. “It kind of feels like fur.”

Senku suddenly feels something brush against his chest, and his heart stops in his throat. Kohaku keeps chipping the stone away, until it comes loose, and Senku steps forward as she stands.

“ What on Earth is this?” she says, moving it in her hands, causing strange feelings to ripple over Senku’s body.

His voice is tight when he finally finds the words, barely able to get it out.

“ It’s my pelt.”

There’s an audible gasp – even a few take a step back – as Senku slowly plucks it out of the shocked Kohaku’s hands, and peels away the foil.

It’s stiff from its protection, but he knows this fur like he knows his own _ name _ . Senku can’t help but smile when he pulls it free, and runs a finger over the two new lightning strike marks just above the eyeholes.

His scars itch from the touch, and he holds it tight to his chest, shoving down the desire to have a complete breakdown. Out of the corner of his eye, he sees every villager suddenly trying to look in any other direction – attempting to give him something resembling privacy, and he smiles, fighting the tears that threaten to come.

A small irrational part of him wants to run straight down to the harbour and dive straight in. The rational scientist however, realises that the pelt is only half the prize. It’s been used to protect an object wrapped in yet more tinfoil.

Senku can’t help but laugh when he realises what it is. Even thousands of years in the future, Byakuya still manages to surprise him.

* * *

The entire village gathers once the record player is complete. Senku has his pelt wrapped around his shoulders, keeping an iron grip on the edges whenever he doesn’t need his hands to work, and everyone gives him space for when they start playing the disc.

“ _ I don’t know who's listening to this. It could be hundreds, even thousands of years from now. Anyway, my name is Ishigami Byakuya. I’m an astronaut- _

The entire village roars in shock, and Senku laughs, sticking a finger in his ear.

“ Shut up will you? I can’t hear,” he jokes. Around him, people are talking in astonishment, but he focuses on Byakuya’s words.

“ _ -But enough about me. Who the hell needs a bunch of stuffy formality. You revived from the petrification, and somehow got your hands on this recording. Senku, you’re listening aren’t you? I can tell. Who knows how many centuries it's been since we’ve seen each other, but this will be the last call I make to you. Of course it’s not like I can hear you or anything. Senku, I want you to know that I always...always...” _

Everyone leans in, to hear the final words of a father to his son.

“ _ Actually, you know what, you’re the last person who needs all that sappy father and son crap!” _

Senku bursts into laughter, even as the villagers collapse in astonishment.

“ He knows me too damn well.”

“ _ I do need to say this though, so bear with me, okay?” the recording continues. “Senku, I can only hope that when you were petrified, you had my pelt with you. That you haven’t gone however long it took to find this disc without one. If you didn’t...I’m so sorry. Hopefully, yours was still in good enough condition. We did everything we could to make sure it would be preserved as long as possible. I promised you that I’d take good care of it after all. I’m just sorry you had to wait so long.” _

Senku’s smile fades at the words.

“ _ But for what it’s worth, I’m glad I had it,”  _ Byakuya continues. _ “Because every day I pulled it over my shoulders, to see if I could inherit it. And every day I failed meant that you were still alive. That the petrification didn’t kill you and everyone else. It gave us hope, even on the worse days, and I wouldn’t have traded that for anything. If nothing else, I had that assurance.” _

His hands pull at his pelt, almost wrapping his entire upper body in the fur, keeping his face impassive, even as a weight he’d been carrying since he broke out of the stone suddenly eases.

_ “Now then, that’s the sappy part over, I promise!  _ _ Senku, if this village is still here, and you’re having a tough time winning over the villagers, I suggest playing this for them-” _

* * *

“ You know, we could go to the hot springs for this-”

Senku laughs. “No way. I can handle some cold. And I’m ten billion percent done waiting.”

He’s standing at the edge of the harbour, watching as Magma, Kohaku and other warriors of the village hack at the ice on the lake. For the first time since waking up in the stone world, he’s itching to enter the water, only managing to avoid pacing to stop Chrome from panicking. 

By his side, Kaseki is chortling, rubbing his hands in excitement.

“ Hahaha, nothing like a good winter’s swim to get the blood pumping, right Senku?” he says. “Time for us selkies to show them how it’s done.”

From where she’s smashing ice, Kohaku looks up and grins. “If that’s a challenge, I’m up for it. I can handle some winter swimming.”

“ Hey, if you’re going in, I’m going in!” Chrome insists. Kaseki immediately claps him on the back.

“ That’s the spirit, boy!”

He then turns his head, to see Gen sitting on the steps up to the village. “What about you Gen? Feeling brave?”

The mentalist makes a show of pulling his outer coat tighter around his neck.

“ Oh I’m staying up here thank you,” Gen says, clearly unimpressed. “You can toss me in come summer, but for now I think anyone who can’t magically grow several kilos of blubber and a fur coat should stay on land.”

“ He’s not wrong,” Senku says. “Appreciate the enthusiasm, but I’d rather not treat anyone for hypothermia or pneumonia this close to spring. Promise once the ice has thawed, you can swim all you want.”

Kohaku pouts, and Chrome frowns, but neither protest.

“ Hah! I’m through!” Magma yells, quickly pulling up his axe and jumping back onto the jetty. The others follow, and Senku pushes past them, to see the large gaping hole in the ice.

It’s appearance triggers something in him. He doesn’t even remember running – only jumping and smashing into the water head first, feeling that rush of cold, before the familiar tingle of his pelt envelops him, shifting and warping his body into something designed to handle this environment. Hands become flippers, legs become a tail, and his cow licked hair vanishes under dark fur.

Once the transformation is complete, Senku flips in the water, swimming at speed around the floating jetty, basking in the feeling he’d forced himself to accept he’d never feel again, sharp teeth flashing in a facsimile of a grin.

A minute later, he pokes his head from the hole, to see everyone staring down at him, ridiculous grins on their faces. Chrome leans over the jetty, looking delighted.

“ Senku?”

Senku replies by spitting a jet of water in his face, and barks a laugh as Chrome splutters and jerks back, before he dives back into the lake, moving at fast speed. Behind him, he can hear splashes, and a few moments later, he’s joined by several other seals – including one short and greying, and one sleek and trim, shadowed by a thin, shorter twin. The pod quickly matches pace with him, and Senku spins as he takes the lead.

He will desperately savour this, he knows. Once they make it back to land, everything has to be about Tsukasa and stopping the war. There won’t be time to embrace the sea, or the pelt his father desperately kept safe for him. However, now he knows there  _ will _ be a next time, and he’s going to enjoy every second of it.

For now? It’s time to guide his new pod to new shores, both land  _ and _ sea.


End file.
